1. Field of the Invention
This invention relates to a valve and more particularly to a diaphragm type valve having a valve member arranged to move between an open and a closed position with a Belleville spring assembly surrounding the valve member and arranged to apply a thrust thereon to move the valve member through a short stroke to an open position.
2. Description of the Prior Art
It is known with conventional Y-type diaphragm valves as disclosed in U.S. Pat. Nos. 3,979,105 and 3,982,729 to support a valve member for axial movement within a valve chamber between an open position removed from a valve seat connecting the inlet and outlet of the chamber and a closed position engaging the valve seat to interrupt flow through the chamber. The valve member is supported for axial movement within the chamber and is advanced into the closed position by downward movement of a valve stem which abuts the top of a flexible diaphragm assembly positioned within the chamber between the valve stem and the valve member. The downward force of the valve stem is transmitted through the diaphragm assembly to the valve member. A coil spring is retained within the chamber around the valve member and is arranged to abut at one end portion a cap of the valve member and at the opposite end portion the shoulder of a spring guide that is supported within the chamber surrounding the valve member. The spring urges the valve member upwardly into contact with the diaphragm to maintain the valve in a normally open position. When the valve member is moved downwardly by the force generated by the valve stem, the coil spring is compressed between the cap and spring guide.
In order to insure engagement of the valve member with the valve seat to seal the valve, it is essential that the valve member be maintained in an axial position within the valve chamber. Deviation from an axial position of the valve member causes deformation of the valve member and/or results in improper seating of the valve member upon closure and renders the valve inoperable to control the flow of fluid between the inlet and outlet. Therefore, unless the valve member is stabilized for axial movement within the chamber the effects of extreme fluid flow and/or vibration may be sufficient to displace the valve member from its axial alignment and prevent complete closure of the valve. Also if the valve member is not securely stabilized within the chamber, it will spin, causing displacement from axial alignment.
It has been the practice to increase the strength of the valve member to resist deformation within the chamber by increasing the mass of the valve member. However, this reduces the area available for the coil spring. Sufficient area must be available to insure that the coil spring exerts a sufficient force to move the valve member through a linear stroke that displaces it from engagement with the valve seat. A problem is presented in providing a suitable spring of a size sufficient to generate a higher stabilizing thrust to move the larger valve member away from the valve seat while maintaining a stabilizing force on the valve member throughout its stroke.
There is need in a diaphragm valve for a spring that is operable to exert an increased higher thrust upon a larger valve member to move the valve member through a relatively short stroke to an open position while stabilizing the axial position of the valve member in the chamber.